Catheter introducer system for exploration of body cavities

ABSTRACT

A self propelling catheter introducer system for exploring a body cavity is disclosed which includes a flexible tubular catheter, an everting tube and a steering section located near the distal end of the catheter that is introduced in a body cavity. The steering section is adapted for pointing the distal end in a desired direction using a plurality of rods adapted to be extended and retracted.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/720,072, filed on Nov. 25, 2003, which is a continuation of U.S.patent application Ser. No. 10/020,913, filed on Dec. 19, 2001, and nowU.S. Pat. No. 6,699,179, which is a continuation in part of U.S. patentapplication Ser. No. 09/492,448, filed on Jan. 27, 2000, and now U.S.Pat. No. 6,517,477, all of which are incorporated herein in theirentirety.

BACKGROUND OF THE INVENTION

The present invention relates to a method and a device for performingendoscopy through a catheter introducer system. In particular, thepresent invention relates to a catheter introducer system for endoscopydesigned to reach the cecum portion of the gastrointestinal tract.

DESCRIPTION OF RELATED ART

Endoscopy has become an increasingly important tool in diagnosing and intreating ailments of the gastrointestinal tract, also referred to as theGI tract. Typical endoscopes are essentially formed by a somewhatflexible tube that is pushed through the GI tract, after beingintroduced in the body cavity starting from the rectum or starting fromthe esophagus. The endoscope has a steerable tip to facilitatenavigation through the GI tract, and typically has to be sufficientlystiff so that it can be pushed further along the body cavity. The tip ofthe endoscope that is introduced in the GI tract can be outfitted withseveral devices, most notably an illumination device and a visiondevice, such as a vision integrated circuit, so that the operator of theendoscope can observe the interior of the GI tract and maneuver theendoscope in the proper position.

Once the endoscope is in position, other tools attached to the endoscopeor inserted through the endoscope can be brought to the proper positionin the GI tract. Various procedures can then be carried out, such asremoving polyps, performing sutures, irrigation, suction, and removingother tissues. The various tools that are used together with theendoscope can be either inserted separately in the GI tract and placedin the proper position independently, or may travel in a working channelof the endoscope, so that once the endoscope is positioned at thedesired location in the GI tract, the tools inserted in the endoscopewill also easily reach that position.

Endoscopes or other smaller similar devices can also be used to exploreother body cavities, for example airways or blood vessels. These probesmust be small to fit in the smaller cavities, and care must be taken toavoid damage to the more fragile membranes lining these cavities.

Current state of the art endoscopes are very capable devices, andendoscopy has been very successful in diagnostic and therapeuticapplications with the use of current endoscopes and the current arsenalof tools that can be inserted through the working channel of theendoscope, or can be attached to the outside of the endoscope. However,current endoscope technology has limitations and drawbacks. One of thegreatest drawbacks of current endoscopes is that the working channel issmall. The working channel is small relative to overall diameter of theendoscope, and is further limited by the space taken up by vision,irrigation, suction, light, and control cabling mechanisms that are partof the endoscope and are required to control the endoscope. Thus thereis a very small area left for other tools to be introduced through theendoscope.

Current endoscopes are also difficult to maneuver, particularly when theendoscope has to be pushed from outside the body all the way to a farportion of the intestine, such as the cecum, located at the beginningportion of the large intestine. Currently, reaching the cecum requirestraining, skill, luck and trial and error on the part of the operator.Current endoscopes have to be maneuvered by pushing them from outsidethe body into the gastrointestinal tract, while steering the far endinside the body cavity. This situation creates an inherently unstablecondition, where a long tube is being pushed through a narrow cavity.This requires the endoscope tube to be rather rigid, resulting indiscomfort to the patient as the endoscope is maneuvered. Because ofthis, the patient often must be sedated.

Once the cecum has been reached, additional tools still have to benavigated through the body to reach the location, and if the endoscopeis withdrawn from that location to make room for other tools, access hasto be reestablished using the same complicated procedure. Currentendoscopes tend to be reusable because of the high cost of theircomponents, and thus require thorough cleaning to sterilize them.Sterilization can be difficult to guarantee, and in many instances adisposable device would be preferable.

Accordingly, there is a need for an improved type of endoscope with aintroducer system that obviates some of the drawbacks of currently knownendoscopes.

SUMMARY OF THE INVENTION

The present invention is directed to a catheter introducer system forendoscopy that substantially obviates one or more of the problems due tolimitations and disadvantages of the related art, and that can be usedmore easily and with less discomfort to the patient. Additional featuresand advantages of the invention will be set forth in the descriptionwhich follows, and in part will be apparent from the description, or maybe learned by practice of the invention. Other advantages of theinvention will be realized and obtained by the apparatus and methodparticularly pointed out in the written description and claims hereof,as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described, the inventiondiscloses a self propelling catheter introducer system for exploring abody cavity that includes a flexible tubular catheter having a lengthextending from a distal end for introduction in the cavity to a proximalend opposite the distal end, a tubular working channel formed within thecatheter, adapted for guiding medical tools along the length of thecatheter, and a steering section of the catheter disposed adjacent thedistal end, adapted for pointing the distal end in a desired direction.In addition, the system includes a flexible everting tube disposed atthe distal end that applies a propulsive force to the tubular catheter,and control unit for controlling operation of the everting tube and ofthe steering section. Examples of everting tube apparatus areillustrated in U.S. Pat. Nos. 5,259,364 and 5,586,968, both to Bob etal.

In another aspect, the invention discloses a method of propelling acatheter for exploring a body cavity, the catheter having an outersurface including a flexible everting tube. The method comprisesinserting a distal end of the catheter through an opening of the bodycavity, securing an anchor portion of the catheter to the opening, thecatheter being slidable in the anchor portion and a surface of theeverting tube being secured to the anchor portion, and translating theeverting tube relative to the anchor portion, thus inserting orwithdrawing the catheter in the body cavity.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention and are incorporated in and constitutepart of the specification, illustrate several embodiments of theinvention and together with the description serve to explain the presentinvention. In the drawings:

FIG. 1 illustrates a first embodiment of the catheter introducer systemfor endoscopy according to the invention;

FIG. 2 illustrates a detail of the distal end of the catheter shown inFIG. 1;

FIG. 3 illustrates a portion of a second embodiment of the catheterintroducer system according to the invention;

FIG. 4 illustrates a portion of another embodiment of the catheterintroducer system according to the invention;

FIG. 5 is a side elevation showing one embodiment of asteering/propulsion section according to the invention;

FIG. 6 is a perspective view showing a detail of one embodiment of agripper portion;

FIG. 7 is a front and side view of a first embodiment of a suction ringaccording to the invention;

FIG. 8 is a front, perspective and side view of a second embodiment of asuction ring according to the invention;

FIG. 9 is a front, perspective and side view of a third embodiment of asuction ring according to the invention;

FIG. 10 is a front and side view of a fourth embodiment of a suctionring according to the invention;

FIG. 11 is a front and side view of a fifth embodiment of a suction ringaccording to the invention;

FIG. 12 is a front, perspective and side view of a sixth embodiment of asuction ring according to the invention;

FIG. 13 is a front and side view of a seventh embodiment of a suctionring according to the invention;

FIG. 14 is a front, perspective and side view of an eight embodiment ofa suction ring according to the invention;

FIG. 15 is a front, perspective and side view of a ninth embodiment of asuction ring according to the invention;

FIG. 15 b is a top view of a variation of the embodiment shown in FIG.15.

FIG. 16 is a diagram showing the interaction of body tissue with asuction hole according to one embodiment of the invention;

FIG. 16 b is a diagram showing the interaction of body tissue with asuction hole according to another embodiment of the invention;

FIG. 17 is a top and perspective view of a tenth embodiment of a suctionring according to the invention;

FIG. 18 is a perspective view of an eleventh embodiment of a suctionring according to the invention;

FIG. 19 is a schematic side view showing the steering/propulsion sectionaccording to one embodiment of the invention;

FIG. 20 is a perspective view of a twelfth embodiment of a suction ringaccording to the invention;

FIG. 21 a is a perspective view of a thirteenth embodiment of a suctionring according to the invention;

FIG. 21 b is a perspective view of another embodiment according to theinvention of a suction ring in a gripper portion;

FIG. 22 is a schematic sectional side view showing a differentembodiment of the propulsion section according to the invention; and

FIG. 23 is a schematic sectional side view showing a further embodimentof the propulsion section.

DETAILED DESCRIPTION OF THE INVENTION

The catheter introducer system according to the present inventionconsists of a large catheter having an outer diameter that may becustomized to fit within the portion of body cavity into which it is tooperate, for example the colon, esophagus, or other part of the GItract. The catheter may be customized to the size of body cavities ofindividual patients. A steerable tip is included at the distal end ofthe catheter that is introduced in the body cavity, so that the devicecan easily travel inside the GI tract or other body cavity that is thesubject of the procedure. A propulsion section may also be included nearthe distal end of the catheter, that operates by pulling the distal endthrough the body cavity, so that the rest of the device is also pulledalong, or by pushing the distal end from inside the body cavity. In thismanner, a very flexible catheter tube can be used. A more flexiblecatheter results in less discomfort to the patient, and can thus be madeof a larger diameter than a rigid catheter could be made. The patientalso does not have to be sedated for this procedure.

The catheter introducer system has several functions, includingnavigation and maneuvering in the GI tract, providing light and visiondevices to see the areas surrounding the tip of the catheter, providingsuction, irrigation and tissue extraction, transporting devices forimage acquisition such as optical and ultrasound sensors, and providinga working channel and tool manipulation for various endoscopy tools.

Because of the design of the catheter according to the presentinvention, a larger diameter tube can be used, so that a large workingchannel is provided for introduction and maneuvering of other tools usedduring endoscopic procedures. The propulsion and steering sections allowthe catheter to maneuver easily in the colon, or in other parts of theGI tract, including hard to reach parts such as the cecum. Once thecatheter is positioned near the area of the GI tract of interest, it canremain there while various tools are introduced through the workingchannel, and thus access to the affected area of the GI tract can easilybe accomplished by successive and different tools. Many components ofthis catheter introducer system are disposable, thus obviating some ofthe problems due to difficult sterilization procedures.

FIG. 1 illustrates a first embodiment of the endoscopy delivery catheteraccording to the invention. Catheter introducer system 1 includes aflexible tubular catheter 2 having a distal end 4 and a proximal end 6.Distal end 4 is the end of the catheter that is introduced in the bodycavity, while proximal end 6 is at the opposite end from distal end 4and remains outside of the body cavity. Flexible catheter 2 is hollow onthe inside, thus defining a working channel 10 that extends fromproximal end 6 to distal end 4. Since the catheter 2 is very flexible,it can have a large diameter, so that a large working channel 10 isprovided for introduction and maneuvering of endoscopy tools 8.

In a preferred embodiment, the working channel is defined by a sheath11, which is non-collapsible and thus tends to maintain a circular crosssection even when it is bent along its axis. Sheath 11 can also includea coil to help maintain its cross sectional shape. The working channeltends to retain a constant size when sheath 11 is used, so that bindingof the tools inserted in the working channel 10 is prevented, and theouter surface of catheter 2 can be very light and flexible. For example,the working channel can have a diameter of about 14 mm, resulting in anouter diameter of the device of about 20 mm.

Various types of tools 8 can be inserted through the working channel 10,so that once catheter 2 is in position within the body cavity,additional endoscopy tools can quickly and easily reach the area ofinterest within the GI tract. Any present tool for endoscopy can beadapted for use in the working channel 10 of catheter 2, and the largecross section of working channel 10 opens the possibility of developingnew tools and procedures that can improve the function of currentdevices. In a preferred embodiment, the catheter portion 2 can bedisposable, so that cleanliness and sterilization of the catheterintroducer system can be assured.

In addition to tools 8 that can be introduced through the catheterintroducer system 1, some other devices can be built-in within catheter2. For example, a vision chip 12 such as a charge coupled device (CCD)or a CMOS and light source 14 can be built in the catheter, as well asan accessory 16 that may perform suction, irrigation, or otherfunctions. In addition to a vision chip 12, other sensors could beprovided on the catheter introducer system 1. For example, X-ray orultrasound sensors could be utilized.

In a preferred embodiment, vision chip 12 and light source 14 can bepart of a modular vision tool 13 that can be detached from catheter 2and replaced. For simplicity, vision tool 13 could snap in place at thefront of catheter 2, so that electrical or other connections would bemade automatically. Using a snap-on vision tool 13 facilitatessterilization of the device, because most components of the catheterintroducer system 1 other than vision tool 13 could be made disposable.If a CCD is used in vision tool 13, only thin wires need to connect theCCD to the proximate end of the catheter 2. Catheter 2 thus remainsflexible and can be manufactured cheaply. If necessary, a fluid supplycould be provided to the CCD lens, to clean it of contaminants.

The catheter portion can be provided with a rectal sheath 20 made of amore rigid material and located at the entrance of the body cavity, forexample to prevent the sphincter from compressing and binding theflexible catheter. Sheath 20 is designed to maintain the sphincter in anopen position and allow the catheter to move back and forth freely. Thesheath may also provide a seal with the outer surface of the catheter.This seal is particularly useful when air is used to inflate the colon,to facilitate the visual inspection. In a further embodiment accordingto the invention, an active sheath can be used to assist the motion ofthe catheter, by pushing and pulling on the catheter, for example withan endless screw mechanism, rack and pinion mechanism, or axial andradial actuators of known type.

The catheter introducer system shown in FIG. 1 includes a propulsionsection 22 that is located near the distal end 4 of catheter 2. Thepropulsion section 22 is designed to pull the portion of catheter 2 nearit through a body cavity, so that the catheter 2 can easily navigatethrough a cavity like the GI tract. Since propulsion section 22 isdesigned to pull from within the body cavity, catheter 2 can be moreflexible than would be possible if the catheter were pushed from outsideof the body cavity, because catheter 2 does not have to transmit thecompression loads caused by being pushed. As a result, this devicereduces the pain and discomfort felt by the patient, because the devicecan be made extremely flexible in bending while also having a largediameter. Propulsion system 22 includes several sliding gripping pads 24that can travel along guides 26 in an axial direction, along the lengthof the catheter 2. Gripping pads 24 are located on an outer surface ofcatheter 2, and in one embodiment are distributed evenly around thecircumference of the catheter 2. In the preferred embodiment shown inFIG. 1, gripping pads 24 have suction ports 25 so that they can attachto the inside surface of the body cavity whenever a vacuum is applied tothe suction port 25.

In a preferred embodiment according to the invention, each one ofgripping pads 24 can move along guide 26 independently, and the suctionapplied to each of suction ports 25 can be turned on or offindependently from that of the other suction ports 25. In a morepreferred embodiment, four gripping pads 24 are provided in four slidingchannels 26, one in each channel, and are spaced about 90° apart fromeach other around the circumference of catheter 2. Opposing pairs ofgripping pads 24 can be coordinated to move and apply suction in unison.

During operation of the propulsion section 22, the gripping pads 24 movein coordinated manner, gripping, releasing, and sliding to move thecatheter 2 forward and backward. To move forward, for example,approximately half of the pads 24 in a first group located at the firstposition A in sliding channel 26 apply a vacuum through suction ports25, so that they become attached to the tissue of the body cavity. Atthe same time, a second group of gripping pads 24 is moved to a secondposition B in sliding channel 26, without vacuum being applied to theirsuctions ports 25. In this phase air may be expelled through the movingsuction ports, to ensure that body tissue does not stick to the movinggripping pads 24. This makes it easier for the gripping pads 24 to slidealong the cavity wall. A saline solution or other fluid may also beexpelled through suction ports 25, to remove any contaminants from theports.

Once the second group of gripping pads 24 reaches position B, the vacuumis turned on to the ports 25 of those gripping pads, which attach to thetissue of the body cavity. Vacuum is at the same time turned off to thefirst group of gripping pads 24 at position A. At that point grippingpads 24 at position B are moved to position A, while maintaining thesuction, so that the entire catheter 2 is pulled forward relative to thebody cavity tissue by a distance substantially equal to the distancebetween points A and B of sliding channel 26.

To move backwards, for example, the same sequence can be carried out inreverse order, so that the group of gripping pads 24 to which a vacuumis applied are initially moved from point A to point B of the slidingchannel 26, to force the catheter 2 out of the body cavity.

Vacuum can be applied to suction ports 25 by turning on and off aconnection to a vacuum source 31. The sliding movement of gripping pads24 and suction ports 25 within sliding channel 26 can be performed in avariety of manners, such as by mechanical movement of push-pull wires30, with force from an inflating bellows, or by activation of linearactuators that respond to electricity or other changes in theiroperating environment. Movement of gripping pads 24 within slidingchannel 26 can also be accomplished in other known manners, such as byusing shape memory actuators, piezoelectric actuators, or other types ofactuators commonly known as artificial muscles.

The application of a vacuum to the various suction ports 25, movement ofgripping pads 24 within sliding channels 26, and other control functionscan be performed by hand or, in a preferred embodiment, by a controlunit 34 that automatically coordinates the movement of the individualsuctions pads in the sliding channels and application of suction inresponse to instructions of the operator of the catheter system. Theoperator, for example, could select movement of the catheter in or outof the cavity, and control unit 34 could operate propulsion section 22accordingly. Control unit 34 could include, for example, a memorycontaining sequences of instructions for movement and application ofvacuum by the gripping pads 24, that result in desired movement of thecatheter 2. Control unit 34 could also include an electronic computer toconvert those sequences into commands for servo motors, valves, andother actuators that affect the operation of gripping pads 24, andcontrol supply of vacuum from vacuum source 31 via ducts 33.

Each of gripping pads 24 could also have more than one suction port 25applying vacuum to the body cavity tissue. A perforated surface could beused instead of an individual port, having a configuration that will bedescribed in detail below, in the context of a perforated suction ring.

In yet another embodiment, different methods for gripping the inside ofthe body cavity could be used instead of the suction pads 24. Forexample, inflatable balloons could grip the tissue of the body cavitywhen inflated, and could be operated in the same manner as the grippingpads with suction ports.

The catheter introducer system shown in FIG. 1 includes a steeringsection 36 also located adjacent to the distal end 4 of the catheter 2.In the preferred embodiment the steering section 36 is closer to theopening of the distal end 4 of the catheter than the propulsion section22. However, the opposite arrangement can also be utilized successfully.Steering section 36 allows an operator to change the direction wheredistal end 4 is pointed inside the body cavity. In the preferredembodiment shown in FIG. 2, the steering section 36 comprises a flexiblestructure, such as a braid or mesh 37, that defines the outercircumferential surface of the tube-like catheter 2. Flexible mesh 37can be collapsed and can also be extended to several times its collapsedlength in a direction along the length of the catheter 2. In a preferredembodiment, steering section 36 is formed of a flexible mesh tube havingsimilar properties to those of an endoscopic or vascular stent, such as,for example, the Wallstent manufactured by Boston ScientificCorporation. The flexible mesh tube is designed to provide sufficientrigidity to maintain a tube-like shape, while also allowing a change inlength of the section.

The tube formed by flexible mesh 37 can also be bent in a desireddirection by stretching mesh 37 in one circumferential portion whilecompressing it on the opposite circumferential portion of the tube.Steering section 36 can thus be turned in a selected direction withrespect to the center line of the catheter 2.

The stretching and turning of flexible mesh 37 can be carried out in aconvenient manner by using push-pull wires 38, shown in FIG. 2.Push-pull wires 38 are sufficiently stiff such that they can carry atension as well as a compression load, and are attached to tip 40forming the distal end 4 of catheter 2. Tip 40 can preferably be made ofaluminum or plastic. In a preferred example, push-pull wires 38 are madeof NITINOL, which is a super-elastic alloy that resists elasticdeformation leading to the formation of kinks. For disposable catheters,the wires 38 can alternatively be made of steel, or other materials thattend to regain their original shape after bending. However, NITINOLwires are preferred for applications where catheter 2 is usedrepeatedly.

Aluminum tip 40, flexible mesh 37, and push-pull wires 38 are alldisposed on the circumference of catheter 2, so that working channel 10is left free for introduction of endoscopy tools. Push-pull wires 38exit the body cavity and exit from catheter 2 at the proximal end 6, andcan be either manually controlled or can be controlled by the controlunit 34. Control unit 34 controls the steering section 36 in a similarmanner as it controls the propulsion section 22.

When push-pull wires 38 are moved together, the length of the steeringsection 36 changes, and the tip 40 on distal end 4 of catheter 2 ispushed further in the body cavity, or is withdrawn partially from thebody cavity. If push-pull wires 38 are acted on differentially, steeringsection 36 can be turned in any direction relative to the length of thecatheter 2. Sutures 42 can be used to attach push-pull wires 38 atdiscrete locations on the flexible mesh 37, to control their positioningand to support them, so they can transmit compression forces withoutbuckling.

Devices other than sutures 42 can be used to hold push-pull wires 38 inposition around steering section 36. For example, rigid rings can befixed at axial locations along the steering section 36, and thepush-pull wires 38 can be attached to the rings, or may be threadedthrough holes formed in the ring's outer portion. Alternatively, simpleclips or loops can be used to tie push-pull wires 38 to specific pointsof mesh 37, so the wires can move only in the axial direction. Heatshrink, polyurethane, or other type of low friction flexible claddingcan be applied on top of flexible mesh 37 and wires 38 to facilitateinsertion and travel of the device within the body cavity. The use of aslippery coating for the catheter makes it easier for the propulsionsection 22 to pull the catheter along the body cavity, and also reducesdiscomfort to the patient. The low friction coating can also be used onthe inside of the cladding, to reduce friction with push-pull wires 38.

In a further embodiment according to the invention, the steering section36 can have an outer surface formed by bellows instead of the flexiblemesh 37. The bellows can be inflated or deflated to extend or contract,in a direction along the length of the catheter 2. Bellows can be alsoextended and contracted by operation of push-pull wires 38, connected totip 40. In this case, the bellows are used simply as an outer cover forthe mechanism of the steering section 36, similarly to mesh 37. Holescan be formed at the crests of the bellows ridges, to guide and keep inplace the push-pull wires 38. The inflatable bellows actuators arefurther described in U.S. Pat. Nos. 5,181,452 and 5,317,952 which arehereby incorporated by reference.

The inflation and deflation, or the extension of various bellowssections can be controlled either by hand or by a control unit 34. Useof the bellows allows steering section 36 to either change its length,or to change the direction where distal end 4 points, in a manneranalogous to that described above.

As a further alternative to a mesh or bellows, a coil structure can beused to maintain the push-pull wires 38 in place, and to give somestructural rigidity to the steering section 36. One or more coils canextend from tip 40 along the length of steering section 36, and can beconnected to wires 38 with any of the methods described above.

Sheath 11 defining working channel 10 preferably can be attached to tip40 but not to mesh 37. In this manner, mesh 37 can change length withoutaffecting the shape of the working channel 10.

FIG. 3 shows a second embodiment of the catheter introducer system forendoscopy according to the present invention. As shown in FIG. 3, atube-like catheter 2 defines a working channel 10 and has a distal end 4designed for introduction in the body cavity. As described above, aresilient sheath 11 can be used to define the working channel 10. Nearthe distal end 4 of the catheter 2, there is a steering/propulsionsection 50 that is used both to pull the rest of the catheter along inthe body cavity that is being explored, and also to direct the distalend 4 of the catheter 2 in the desired direction.

Steering/propulsion section 50 comprises a steering/elongation portion52 that provides elongation as well as steering functions for thecatheter introducer system 1′. For example, steering/elongation portion52 can be formed by a mesh with push-pull wires similar to the onedescribed in FIG. 2. If the push-pull wires are extended or withdrawn atthe same time, steering/elongation portion 52 elongates and distal end 4of the catheter 2 is extended further or is withdrawn from the bodycavity. If the push-pull wires on one side of steering/elongationportion 52 are extended, while those generally on the opposite side ofthe steering/elongation portion 52 are withdrawn, thesteering/elongation portion 52 will turn towards the withdrawing wires,thus changing the direction in which distal end 4 is pointed. Acombination of elongation and turning commands can also be givensimultaneously to the steering/elongation portion 52. In a preferredembodiment, three wires 38 are equally spaced at 120□ intervals aroundthe circumference of the steering/elongation portion 52, and can provideelongation and steering as described above.

Preferably, steering/elongation portion 52 is formed of a flexible meshtube to which are attached push-pull wires 38. This configurationretains a large hollow working channel 10 inside the device because theintegrated steering and propulsion mechanism takes up little wallthickness. Steering/propulsion section 50 also includes a proximalgripper portion 54 and a distal gripper portion 56 that are respectivelypositioned at the proximal and distal ends of steering/elongationportion 52. Both the proximal and distal gripper portions 54 and 56preferably include gripping pads 58 that have suctions ports 59 that canselectively apply suction to the surrounding inner surfaces of the bodycavity.

In the preferred embodiment, suction ports 59 are connected to a vacuumsystem with a source 31 and ducts 33, so that when the vacuum is turnedon the suction port 59 will attach to the tissue of the surrounding bodycavity. When the vacuum is turned off, suction port 59 releases its gripon the inner surface of the body cavity. In a different embodiment ofthe invention, one or both of the proximal and distal gripper portionscan include other means of attaching themselves to the inner surface ofthe body cavity, such as inflatable balloons, suction arms, or otherknown devices.

In a different embodiment, proximal and distal gripper portions 54, 56can include a perforated suction ring to apply vacuum to the surroundingbody cavity tissue, instead of discrete gripping pads 58 with suctionports 59. Several configurations of perforated suction rings will bedescribed below.

In another embodiment according to the invention, steering/elongationportion 52 can include, for example, inflatable bellows as describedabove with reference to the steering section 36, instead of push-pullwires and flexible mesh. In yet another embodiment according to theinvention, the push-pull wires can be replaced by linear actuators 70embedded within the flexible structure of catheter 2, as shown in FIG. 4and as earlier described.

Gripper portions 54, 56 move alternatively closer and farther apartduring the progression of catheter 2. The structures withinsteering/elongation portion 52 must therefore allow this movement. Forexample, as shown in FIG. 19, sheath 11 defining working channel 10 canbe formed by a flexible membrane 150 surrounded by coils 152. Thisconstruction results in a sheath 11 that can extend and contract axiallywhile retaining a constant cross section, and provides a smooth innersurface to the working channel 10. The tubes that provide suction todistal gripper portion 56 also have to extend and contract axially. Thiscan be achieved, for example, using bellows shaped tubes 154, or usingtelescoping flexible tubes 156, with seals 158 placed between thetelescoping sections.

The catheter introducer system 1′ shown in FIG. 3 includes an extremelyflexible catheter 2 and is designed to pull itself along the body cavitywhere it is introduced, rather than being pushed as is done withtraditional endoscopes. The catheter moves in an inchworm fashion bycoordinated motion and control of the gripper portions and of thesteering/elongation portion.

For example, to move forward, the proximal gripper portion 54 attachesto the tissue of the body cavity by applying a vacuum to suction ports59 of the proximal gripper portion 54. The steering/elongation portion52 is then extended, so that the distal gripper portion 56 is pushedfurther inside the body cavity. Suction ports 59 of distal gripperportion 56 then apply a vacuum to the surrounding tissue so as to attachto the tissue, and the suction ports 59 of the proximal gripper portion54 stop applying a vacuum. In a preferred embodiment, suction ports 59can also eject pressurized air to completely release the surroundingtissue. At that point steering/elongation portion 52 is contracted whilethe distal gripper portion 56 continues to attach to the surroundingtissue, so that the portion of the catheter behind distal gripperportion 56 is pulled along inside the body cavity by a distancesubstantially equal to the contraction distance of steering/elongationportion 52. The process is then repeated until the distal end 4 of thecatheter 2 reaches the desired position inside of the body cavity.

To move backward, the above process is reversed. For example, theproximal suction gripper 54 attaches to the tissue, while the distalgripper portion 56 releases the surrounding tissue. Steering/elongationportion 52 is contracted, so that the distal end 4 of the catheter 2 iswithdrawn from the body cavity. Proximal gripper portion 54 thenreleases the tissue, distal gripper portion 56 attaches to the tissueand the steering/elongation portion 52 is extended, so that the portionof the catheter 2 behind distal gripper portion 56 is withdrawn from thebody cavity. The order of attachment and release of grippers 54 and 56can also be reversed, as long as the contractions and extensions ofsteering/elongation portion 52 cause the catheter to be respectivelypulled towards or pushed away from a gripper portion 54, 56 that isattached to the tissue of the body cavity.

The catheter 2 can also simply be pulled out of the body cavity by theoperator. These steps are repeated until the entirety of catheter 2 isextracted from the body cavity. Throughout the operation, steering isachieved by bending the steering/elongating portion 52 either while theinsertion or extraction movement is carried out, or separately while thecatheter 2 remains in position. As shown in FIG. 1, a control unit 34can be used to coordinate the operation of steering/propulsion section50, such as bending and elongation of steering/elongation portion 52,and application of suction.

The second embodiment according to the invention shown in FIG. 3 alsoprovides a large working channel 10 through which various endoscopytools can be inserted and positioned easily in the desired portion ofthe body cavity. A tool ideally suited for this device is a suctionpolypectomy device to remove polyps from the intestine. Theeffectiveness of such device is currently limited by the small workingchannel of existing endoscopes, but this drawback is resolved by usingthe catheter introducer system according to the invention.

Several variations can be made to the design of the gripping pads 58 and24 described above in conjunction to the embodiments of the inventionshown in FIGS. 1 and 3. These variations are designed to maximize thetraction or gripping force exerted by the gripping pads on thesurrounding tissue of the body cavity.

In one embodiment shown in FIG. 5, the gripping pads 58 can be replacedby a perforated suction ring 100, having an outer surface 104 with aplurality of holes 102. Independently controllable sources of suctionand compressed air are provided to gripper portions 54′, 56′, which canbe moved close together or apart along the steering/elongation portion52, as described above with reference to FIG. 3. In this example,suction is applied to the surrounding tissue through holes 102. Holes102 are designed to distribute the suction over a large area of tissue,so that the traction force generated is increased. A suction ring 100with multiple holes 102 also reduces the chances that holes 102 will beclogged by the tissue, or other debris or contaminants. To furtherprevent clogging, provisions can be made to eject pressurized air or aliquid from holes 102, to force any contaminants out of holes 102.

Suction ring 100 also defines a buffer area, or plenum 101 disposedbetween the perforated outer surface 104 and the suction connection duct33, as shown in FIG. 6. Plenum 101 is used to separate the suction duct33 from the holes 102 on suction ring 100, so that suction isdistributed to a larger area of tissue, and clogging of the vacuumsupply is prevented. Plenum 101 can be, for example, an enclosedtoroidal volume between surface 104 and the center of suction ring 100.Plenum 101 may also be divided in non-communicating portions, eachconnected to a different section of suction ring 100.

An additional perforated screen can be placed under the surface ofsuction ring 100. This additional screen has holes smaller than holes102, and acts as a filter to further prevent clogging of duct 33. Holes102 can have a size optimized to maximize suction, while the holes ofthe additional screen are optimized to stop contaminants.

The push-pull wires used to control turning and elongation of thecatheter travel across at least one of the suction rings 100 beforereaching the distal portion 4 of catheter 2. Thus the wires must beinsulated from the suction source, to prevent vacuum leaks. For example,as shown in FIG. 5, the wires 38 could pass through a passage 120drilled through suction ring 100, sealed from the portions connected tothe suction. Alternatively, wires 38 could pass through a sealed tubecrossing plenum 101.

In different embodiments, holes 102 do not have to be uniformlydistributed around the outer surface 104 of perforated suction ring 100.For example, as illustrated in FIG. 7, the holes can be grouped inperforated sectors 106 separated by sectors 108 that are not perforated.Sectors 106 may be connected to separate sources of suction, so that ifone of the sectors becomes detached from the tissue, the remainingsectors will not be adversely affected, and will continue to apply fullsuction to the portions of tissue to which they are attached. In oneexample, holes 102 can have a diameter of approximately 0.04 in., andsectors 106 can extend for approximately 85 degrees of arc, and can beequally spaced around the circumference of suction ring 100.

As shown in FIG. 8, holes 102′ having a different size can be utilizedon suction ring 100. For example, holes of a diameter of about 0.02 in.can be formed. The size of the holes is optimized to obtain the bestsuction without excessive clogging. Smaller and more numerous holes tendto grip better the tissue, but clog more easily. Fewer larger holes clogless, but also tend to provide less traction on the tissue. Differentsizes of holes can be used in all the configurations of suction ring 100described here.

In a different embodiment, portions of suction ring 100 having holes 102can be recessed with respect to the rest of the outer surface 104 ofsuction ring 100. For example, as shown in FIG. 9, recessed portions 121have a plurality of holes 102 to apply suction to the surroundingtissue. The remaining sectors 108 are not perforated. The purpose ofthis design is to obtain a configuration of the suction holes 102 thatincreases traction by drawing portions of the body tissue in recessedportions 121. As the previous configurations, the recessed pattern ofFIG. 9 could be made with different size holes, and could encompassdifferent portions of suction ring 100.

FIG. 10 shows a configuration of suction ring 100 that is especiallyadvantageous when the body cavity is inflated with a gas, to facilitatevisual inspection and passage of medical instruments. When a gas isforced in the cavity, such as the colon, it passes around the catheter,and tends to detach portions of the outer surface of suction ring 100from the surrounding tissue. If a portion of perforated suction ring 100is detached, the rest of suction ring 100 also is likely to becomedetached from the tissue, especially if outer surface 104 is uniformlyperforated. Axial ridges 122 assist in the formation of folds in thetissue surrounding the suction ring 100. The gas forced past suctionring 100 can thus flow in a passage formed by the tissue folds, so thatsectors 106 remain attached and keep the suction ring 100 in place.

FIG. 20 shows another design that allows passage of gases forced throughthe cavity. Suction ring 100 includes perforated sectors 106 separatedby grooves 160. Grooves 160 provide a channel for flowing gases, whileperforated sectors 106 remain attached to the surrounding tissue.

In certain applications, it may be desirable to apply suction to only aportion of the circumference of suction ring 100. FIG. 11 shows oneexample of such application, where a perforated sector 106 extends overan arc of approximately 85 degrees, and the rest of suction ring 100 isnot perforated. As described above, the pattern and size of holes 102can be optimized as desired. In addition, various features alsodescribed above can be included in this design, such as axial ridges 122shown in FIG. 12, and a recessed construction of perforated sector 106,shown in FIG. 13. As before, the purpose of these features is tomaximize traction and prevent separation of the entire suction ring 100from the body cavity tissue.

FIG. 14 shows a further embodiment of the suction ring 100, where theperforated sector 106 is recessed, and is further surrounded byperipheral ridges 126. Peripheral ridges 126 are disposed around therecess 124, and protrude above the outer surface 104 of suction ring100. Peripheral ridges 126 act as a seal that separates the portion ofcavity tissue on which perforated sector 106 applies a suction, and therest of the cavity tissue. In this manner, fluids can flow through thebody cavity while the catheter 2 is inserted in the body cavity. Theflow can pass between the non perforated sectors 108 of suction ring 100and the body tissue, while perforated sector 106 together withperipheral ridges 126 maintains a suction against the tissue, and isthus anchored in place.

As shown in FIG. 15, suction can be applied to the tissue by slots 132,rather than by round holes 102 described above. Slots 132 can be usedwith any of the configurations described, and can be disposedperpendicular to the relative motion of catheter 2, as shown in FIG. 15b.

The several configurations of suction ring 100 are especially wellsuited for use in conjunction with the proximal and distal gripperportions 54, 56 shown in FIG. 3. However, the same configurations canalso be successfully utilized to maximize the traction generated bygripping pads 24 shown in FIG. 1.

The traction force that can be generated by the propulsion sections ofcatheter 2 can be increased by increasing the folds and undulations ofthe cavity tissue in contact with the suction ring 100, thus generatingan interference between the tissue of the inner surface of the bodycavity and fixed protrusions of the gripping pads 24, 58. For example,suction can be used to draw some tissue in holes, slots or betweenprotrusions formed on suction ring 100. Folds in the tissue theninteract with the edges of these structures to generate a force opposingthe relative motion between the tissue and suction ring 100 greater thanwould be possible if the two were simply sliding past each other.

FIG. 16 shows one possible exemplary embodiment utilizing thisprinciple. Tissue 200 of the inner surface of a body cavity is partiallydrawn inside hole 102 formed in perforated sector 106 of suction ring100. As suction ring 100 mounted on catheter 2 is moved in a relativedirection A, a force F_(A) resisting the relative motion is applied bythe portion of tissue 200 that is drawn by suction inside hole 102. Tofurther increase this traction force, means can be employed to urge theportion of tissue 200 drawn within hole 102 against the perimeter ofhole 102. For example, inflatable parts 150 could be inflated, as shownby dashed line 152, to hold tissue 200.

In a different embodiment shown in FIG. 16 b, after being drawn insidehole 102, tissue 200 can be trapped between a sleeve 153 and theperimeter of hole 102. For example, sleeve 153 can be concentric withthe suction ring 100, and be rotatable or translatable just inside ofouter surface 104.

A different exemplary embodiment of a design to increase traction forcesis shown in FIGS. 17 and 18. In this case, protrusions extend from thesurface of suction ring 100 to interact with the tissue that is drawnbetween the protrusions by suction. As shown in FIG. 17, the protrusionscan be, for example, ridges 136 disposed in a substantiallycircumferential direction around suction ring 100. Suction holes 102 canbe disposed between the ridges 136, or even on the raised sides of theridges 136. Instead of ridges, suction ring 100 can have a “soap dish”surface construction, where a plurality of studs 138 extend from theouter surface, and are interspersed with suction holes 102. Thisembodiment is shown in FIG. 18. To maximize the resistance to relativemovement between the catheter and the tissue, the studs can be staggeredin the direction of relative movement. The designs shown in FIGS. 17 and18 take advantage of the same mechanism described with reference to FIG.16.

The force exerted by gripper portions 54, 56 can also be varied bychanging the axial length of suction ring 100, and the number of rows ofholes 102. For example, FIG. 21a shows a suction ring 100′ having twoadditional rows of holes 102, in the axial direction of the catheter.FIG. 21 b shows the same suction ring 100′ used in a gripper portion 54,56, to generate a greater force.

An example of how the catheter introducer system according to theinvention can be used will now be described with reference to FIGS. 1through 3. A common procedure in endoscopy is the examination of thecolon and removal of polyps present in the colon. A vision light tool(VLT) is inserted into the steering catheter 2 and is secured to the endof the catheter 2. Catheter 2 is then inserted into the rectum using arigid sheath 20. The catheter 2 is then driven through the intestinetowards the cecum while being guided and controlled by a control unit34. In one embodiment according to the invention, control unit 34includes a monitor through which the operator can view what is beingtransmitted by the VLT, so that he can drive the catheter forward orbackwards while simultaneously steering it. During tests, the propulsionsection was able to resist a pulling force of approximately 2.5 lbs.while remaining attached in position in a colon by suction.

After reaching the cecum, the device is then slowly pulled back from thececum to the rectum, as the interior of the intestine is inspected. Whena polyp is sighted, a suction polypectomy device is inserted into thecatheter until it protrudes from the distal end 4 of catheter 2, and isseen on the monitor by the operator. The suction polypectomy tool issteered to the polyp, and the polyp is excised and withdrawn by vacuumthrough the suction channel of the polypectomy tool. Additional toolscan be introduced and brought into position at the site of interestrapidly and easily through working channel 10, because catheter 2maintains access to the operation site while various tools are withdrawnand inserted back into the catheter.

In a preferred embodiment according to the invention, the variousdiagnostic and therapeutic tools used in endoscopy are positionedaccurately with respect to the body cavity by moving the distal end 4 ofthe catheter 2 with the steering section 36, or with thesteering/propulsion section 50. In a different embodiment, still withinthe scope of the invention, the endoscopic tools can be positionedaccurately by using a separate positioning system, which could includepush-pull wires 72 similar to those shown in FIG. 2, or a systemincluding inflatable bellows, linear actuators, or a combination ofthese devices. Also in a preferred embodiment according to theinvention, many components of the catheter introducer system aredisposable, thus assuring a high degree of sterility to the device. Forexample, the flexible tube of catheter 2 can be disposable, as well asvarious portions of the endoscope tools 8 used within working channel10.

In a different embodiment of the catheter introducer system according tothe invention, the steering section may be separate from the propulsionsection, and the propulsion section includes an everting tube thatprovides the force to push the catheter further in the body cavity. Asshown in FIG. 22, catheter 2 has a distal end 4 that is introduced inthe body cavity, and a steering section 36 analogous to the steeringsection described with reference to FIG. 1. Propulsion section 300includes an everting tube mechanism that pushes from inside the bodycatheter 2 along the body cavity.

Everting tube mechanism 302 includes a flexible everting tube 304 thathas an external surface 306 divided into an outer portion 309 and aninner portion 308, separated by a fold 310. An anchor 312 may be mountedaround the catheter 2 and everting tube 302, and may be secured so thatit does not move relative to the body cavity. For example, anchor 312can be secured to the opening of the body cavity. The outer portion 309of the everting tube 302 may be securely attached to anchor 312, whilethe inner portion 308, together with catheter 2, is free to slidablytranslate relative to anchor 312. An analogous design which is not showncan also be produced where the inner portion is attached to an anchorelement, while the outer portion is free to translate with the catheter,relative to the anchor element.

The lengths of inner and outer portions 308, 309 are not constant. Aswill be described below, the fold 310 is forced to move away from anchor312 to propel the catheter. As fold 310 moves away from anchor 312, thelength of flexible tube 304 between anchor 312 and fold 310 increases.Because outer portion 309 is attached to anchor 312, the increasedlength is provided by a section of inner portion 308 that is turned overat fold 310, and becomes part of outer portion 309. At the same time,the portion of flexible tube 304 on the opposite side of anchor 312decreases in length as inner portion 308 translates past anchor 312.

A drive system is used to cause the flexible tube 304 to translaterelative to the body cavity. In one embodiment, a fluid is providedinside of flexible tube 304. The fluid is pressurized so that flexibletube 304 is kept somewhat rigid, and to provide a force that pushes fold310 away from anchor 312. For example, a pressurization system 314 canprovide fluid pressurized by a pump that is conveyed to flexible tube304 by fluid distribution lines 316. A control unit 320 can be used, forexample, to operate the pressurization system 314 via control lines 322.In one exemplary embodiment, a greater fluid pressure can be applied tothe portion of the flexible tube 304 between anchor 312 and fold 310, sothat the pressure forces fold 310 to translate away from anchor 312. Inthis exemplary embodiment one skilled in the art would appreciate that aseal 328 attached to the outer portion 309 and abutting the innerportion 308, such that inner portion 308 can slidably translate adjacentthe seal, would permit the pressure force to translate fold 310 awayfrom anchor 312.

A second pressurization system 332 can also be included to pressurizelubricating fluid placed between the everting tube 304 and the surfaceof the catheter 2. As shown in FIG. 23, a fluid pocket 330 can be formedand filled with fluid to lubricate the relative movement of the evertingtube 304 and the catheter 2. This second pressurization system 332reduces frictional forces caused by movement of the everting tube 304relative to the catheter 2. The second pressurization system 332 can beused to pressurize the fluid in pocket 330, under the control of acontroller 334. Alternatively, control unit 320 and pressurizationsystem 314 can also be used to control the state of the fluid in pocket330.

In one exemplary embodiment shown in FIG. 22, a thrust collar 327 isattached to catheter 2, and is shaped to receive the fold 310 offlexible tube 304. In this manner, as fold 310 is forced away fromanchor 312, a force is applied to thrust collar 327, and the entirecatheter 2 slidably translates in a direction away from anchor 312. Inone embodiment, the fluid that pressurizes flexible tube 304 is alubricant used to facilitate movement of the inner and outer portions308, 309 relative to other components of the everting tube.

In a different embodiment of the everting tube according to theinvention, the drive system includes a mechanical drive used totranslate the inner portion 308 of flexible tube 304 away from ortowards anchor 312. This motion, in turn, causes catheter 2 to move inthe same direction. In one exemplary embodiment, the mechanical driveincludes wheels 324 that rotate to impart a translational movement toinner portion 308. Wheels 324 can be, for example, gears or frictionwheels that engage the flexible tube. Propulsion for the wheels 324 canbe provided by a transmission mechanism or a gear drive extending alongcatheter 2, or by a remote system actuating the wheels by magnetism orother interaction.

Control unit 320, or a separate control unit, can be used to actuatewheels 324 of the drive mechanism. As indicated in FIG. 22, wheels 324can rotate in either direction, to further insert or to retract catheter2 from the body cavity. A combination of a mechanical drive and ofpressurized fluid, as described above, can also be used to positivelycontrol the movement of catheter 2. Retraction may be accomplished byattaching another thrust collar (not shown) adjacent the proximal end 6of catheter 2 that is shaped to receive another fold located at theproximal end of the flexible tube 304. In this manner, as the proximalthrust collar is forced away from anchor 312, a force is applied to theproximal thrust collar, and catheter 2 slidable translates in adirection away from anchor 312 and out of the patient's body. Catheter 2may also be retracted by exerting a pulling force on catheter 2separately or in conjunction with the drive units discussed above.

In one embodiment, the everting tube can be manufactured from a materialhaving azotropic properties, so that it will stretch in one direction,but resist stretching in the perpendicular direction. For example, theeverting tube can be made of Silicone, PTFE or PE. The everting tube canbe made with or without reinforcing material such as a braid 329.

As indicated, the catheter introducer system of the present inventioncould be used to navigate within body cavities other than the GI tract.For example, air passages or blood vessels could be explored using thissystem. For blood vessels, it would be necessary to reduce the size ofthe apparatus, and preferably to only use the steering section, to avoidinterference with blood flow through the vessel. For example, an outerdiameter of the device would have to be less than about 2 mm.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the structure and themethodology of the present invention, without departing from the spiritor scope of the invention. Thus, it is intended that the presentinvention cover the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents.

1. A self propelling catheter introducer system for exploring a bodycavity, comprising: a flexible tubular catheter having a lengthextending from a distal end for introduction in the cavity to a proximalend opposite the distal end; a tubular working channel formed within thecatheter, adapted for guiding medical tools along the length of thecatheter; a steering section of the catheter disposed adjacent thedistal end, adapted for pointing the distal end in a desired direction;and an everting tube applying a propulsive force to the tubularcatheter.
 2. The system according to claim 1, further comprising acontrol unit for controlling operation of at least one of the evertingtube and steering section.
 3. The system according to claim 1, furthercomprising a light vision tool detachably connected to the distal end ofthe catheter.
 4. The system according to claim 1, wherein the evertingtube comprises: a flexible tube having an external surface folded onitself, the external surface defining an outer portion substantiallynon-moving relative to the body cavity, and an inner portion adjacentthe tubular catheter; at least one thrust collar secured to the tubularcatheter, adapted to transmit a force from the flexible tube to thetubular catheter; and a drive unit adapted to selectively translate theinner portion relative to the outer portion of the external surface. 5.The system according to claim 4, further comprising an anchor disposedaround the tubular catheter at a point of entry of the body cavity, theanchor being substantially stationary relative to the body cavity. 6.The system according to claim 5, wherein the outer portion is attachedto the anchor.
 7. The system according to claim 5, wherein the innerportion is attached to the anchor.
 8. The system according to claim 4,wherein the drive unit is a gear drive to translate longitudinally theinner portion.
 9. The system according to claim 4, wherein the driveunit is powered from outside the body cavity.
 10. The system accordingto claim 8, wherein the gear drive applies a force to a surface of theflexible tube.
 11. The system according to claim 4, wherein the flexibletube material has azotropic properties.
 12. The system according toclaim 4, wherein the flexible tube is made of one of silicone, PTFE, andPE.
 13. The system according to claim 4, wherein the flexible tube ismade with a reinforcing material.
 14. The system according to claim 13,wherein the reinforcing material is a braid.
 15. The system according toclaim 4, wherein the flexible tube contains a fluid.
 16. The systemaccording to claim 15, wherein the fluid is a lubricant.
 17. The systemaccording to claim 4, wherein the drive unit comprises a pressurizedfluid selectively applying a pressure force to an internal surface ofthe flexible tube.
 18. The system according to claim 17, furthercomprising a pump for pressurizing the pressurized fluid and a line fordistributing the pressurized fluid.
 19. The system according to claim17, further comprising a control unit for controlling pressurization ofthe fluid contained in the everting tube.
 20. The system according toclaim 8, further comprising a control unit for controlling movement ofthe gear drive.
 21. The system according to claim 4, further comprisinga control unit for controlling operation of the drive unit.
 22. Thesystem according to claim 1, wherein the steering section comprises aplurality of push-pull wires secured to the distal end of the catheter,circumferentially disposed along the length of the catheter, adapted tobe individually extended and retracted to point the distal end in thedesired direction.
 23. The system according to claim 22, wherein thesteering section further comprises a flexible tube-like structure toguide movement of the plurality of push-pull wires.
 24. The systemaccording to claim 1, wherein the steering section comprises bellowsthat can be extended and contracted in a direction along the length ofthe catheter, and control wires disposed circumferentially around thecatheter to control extension of the bellows, thus pointing the distalend in the desired direction.
 25. A method of propelling a catheter forexploring a body cavity, the catheter having an outer surface includingan everting tube, comprising: inserting a distal end of the catheterthrough an opening of the body cavity; securing an anchor portion of thecatheter to the opening, the catheter being slidable in the anchorportion, a surface of the everting tube being secured to the anchorportion; and translating the everting tube relative to the anchorportion, thus inserting into or withdrawing the catheter from the bodycavity.
 26. The method according to claim 25, further comprisingproviding a pressurized fluid in the everting tube, such that afolded-over end of the everting tube translates relative to the anchorportion, the folded-over end abutting a thrust collar secured to thecatheter to apply a propulsive force to the catheter.
 27. The methodaccording to claim 25, further comprising activating a drive mechanismto translate a portion of the everting tube in contact with the catheterrelative to the anchor portion.